Wednesday, November 29, 2023


Ask Dave: Should I fill all my RV’s tanks with water during winter storage?

Answers to questions about RV Repair and Maintenance from RV expert Dave Solberg, author of the “RV Handbook” and the managing editor of the RV Repair Club. This column appears Monday through Saturday in the RV Travel and RV Daily Tips newsletters. (Sign up for an email reminder for each new issue if you do not already receive one.) Today Dave answers a reader’s question about filling all of the RV’s tanks with fresh water during winter storage.

Dear Dave,
When storing our coach for the winter (inside and plugged in), should we fill our fresh, gray, and black tanks with fresh water? Thanks! —David, Tiffin Allegro Bus

Dear David,
I would drain every tank and clean them out thoroughly, as sitting water can get skunky and develop bacteria pretty fast. Plus, the black water tank will have holding tank chemicals and sewage in it.

How to clean the RV’s tanks for storage

First, I would drain the black water tank and then fill it back up with fresh water, either through the black water flush valve, or a handheld wand through the toilet. This will help flush the tank again and especially clean off the monitor panel probes. I also use a clear adapter at the bayonet or end of the hose to see the condition of the dump fluid. You will be amazed at how dirty the second dump is. I usually dump it one more time just to be safe. Then I put in Thetford Drain Valve Lubricant to keep the rubber seal in the spade valve sealed.

After that, I dump the gray water tank and fill it again with fresh water and dump in some Thetford Gray Water Tank Treatment to make sure all soap and other items are flushed out. Then I dump again. I use the Valve Lubrication here as well. And finally, the fresh water tank, lines, pump, and water heater are completely drained.

One word of caution

If you are plugging in your unit, make sure it’s plugged into a dedicated outlet, not one that is ganged to others inside the building or garage. And make sure it’s wired with the proper power, as most residential plug-ins are either 10 or 15 amps. Run nothing but your converter, as it will draw about 9 amps. If you have anything else on, you could overload the circuit.

Read more from Dave here

Dave Solberg worked at Winnebago for 15 years developing the dealer training program, as marketing manager, and conducting shows. As the owner of Passport Media Creations, Dave has developed several RV dealer training programs, the RV Safety Training program for The Recreation Vehicle Safety and Education Foundation, and the accredited RV Driving Safety program being conducted at rallies and shows around the country. Dave is a leading expert in the RV industry and author of the “RV Handbook” as well as the Managing Editor of the RV Repair Club.


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Dave Solberg
Dave Solberg
Dave Solberg is a leading expert in the RV industry and author of the “RV Handbook” as well as the Managing Editor of the RV Repair Club. He has been in the RV Industry since 1983 and conducts over 15 seminars at RV shows throughout the country.



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Marty (@guest_144786)
2 years ago

These are great recommendations. However how many of us have a dump station where we can stay in place for hours filling, dumping, refilling and dumping again hundreds of gallons from multiple tanks? I only wish I had one at home. The public ones typically have others impatiently waiting in line for you to finish up and move out of the way as quickly as practical.

Bob Weinfurt (@guest_143855)
2 years ago

Before draining the system, be sure the water heater is shut off or you’ll burn out its electric heating element.

Ron V (@guest_143818)
2 years ago

I think there is a typo near the end under “One word of caution.”
Residential plug-ins are either 20 or 15 amps not “10 or 15.”

Thomas D (@guest_143711)
2 years ago

What a dumb question. Ask yourself this. Do you want water in your tank that will be conceiving moldy next time you use it? Of course, get every drop of water out of the system, blowing it out with air compressor if necessary.
As for plugging in the coach,, maybe. I found out the hard way that having a battery maintainer on 24/7 will ruin a battery. I bought a very expensive maintainer for my golf car and 5 months later the batteries were DRY. I called the co that made it and was told ” if any cell is bad the maintainer will attempt to charge it to float voltage. In order to do that the current will boil the other cells. Now I use a timer for just 2 hours a day

Diane Mc (@guest_143722)
2 years ago
Reply to  Thomas D

Thought the question was should he fill the tanks with fresh water while in storage. Which led me to believe he had dumped & cleaned the tanks.

Bill (@guest_143679)
2 years ago

In addition, either blow out the fresh water lines with low pressure air, or run RV/potable water safe antifreeze through all the lines and a little into the tanks, or both. It doesn’t take much water freezing in a low point to cause damage, and draining doesn’t get all the water out of all the plumbing. You do have to flush it out and sanitize in the spring.

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